Electron beam display device



p 1965 w. H. WILBANKS ETAL 3,207,936

ELECTRON BEAM DISPLAY DEVICE Filed Aug. 21, 1961 2 Sheets-Sheet lRESISTANCE DISTANCE FROM COATING 30 (IN INCHES) F lg. I2

WVEA/TORS. WILLIAM H. WILBANKS ROBERT H. JOHNSON CHAN H WANG FRANK C.ERZEN B Y BUCKHORN, CHEA THAM a BLORE AT TORNE Y5 Sept. 21, 1965 w. H.WILBANKS ETAL 3,207,936

ELECTRON BEAM DISPLAY DEVICE 2 Sheets-Sheet 2 Filed Aug. 21, 1961 s NHMO w m IH m mw V .J

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BUCKHORN, CHEATHAM 8 BLORE ATTORNEYS United States Patent 3,207,936ELECTRON BEAM DISPLAY DEVICE William H. Wilbanks and Robert H. Johnson,Hillshoro,

and Chan H. Wang and Frank C. Erzen, Portland,

Greg, assignors to Tektronix, Inc., Beaverton, Greg,

a corporation of Oregon Filed Aug. 21, 1961, Ser. No. 132,915 16 Claims.(Cl. 31375) The subject matter of the present invention relates ingeneral to improvements in electron beam display devices, andspecifically includes improved envelope structure for such displaydevices.

The envelope structure of the present invention is particularly usefulin a cathode ray tube type of display device, such as that employed in acathode ray oscilloscope, so that it will be described in detail withreference thereto.

Briefly the envelope structure of the present invention includes: anenvelope having a body portion made of ceramic material with one end ofsuch body portion having a hollow cross-section substantially in theshape of a rectangle, and a face plate portion made of transparent glassin the form of a substantially flat rectangular plate of a shapeconforming to that of such one end of such body portion and attached tosuch one end of such body portion by a seal portion made of a glass fritmaterial having a thermal coeflicient of expansion similar to and asoftening temperature below that of such ceramic and such transparentglass; a resistance coating of noncarbon refractory material on theinner surface of such ceramic body portion of such envelope, which mayhave a varying thickness and a graduated resistance per square and beelectrically connected tofunction as a post deflection accelerationanode electrode; and a graticule scale provided on the inner surface ofsuch flat face plate portion of such envelope so that such graticule canbe illuminated by Light projecting into such face plate portion throughthe edge surrounding the periphery thereof.

Conventional cathode ray tubes are formed with envelopes made entirelyof glass having circular or rectangular face plates supporting thefluorescent screens thereof. These circular face plate cathode ray tubestake up much unnecessary space in a cathode ray oscilloscope because theupper and lower portions of the circular fluorescent screen are seldomif ever used to reproduce the electrical signal wave form underinvestigation. It is difficult .to make a glass envelope with arectangular shape because the side Walls tend to deform inwardly duringhigh temperature evacuation and cracks form at corners having a smallradius of curvature, due to stress within the glass. Therefore, when theconventional glass envelopes are shaped to provide a molded rectangularface plate the corners of .the rectangular funnel portion must be madeof greatly increased thickness for strength which also cuts down on theusable surface area of such face plate. Also, the molded glass faceplates of conventional cathode ray tubes are curved rather than flat andas a result require an additional flat, external graticule plate placedin contact with the external surface of the face plate in order toprovide an edge-lighted graticule for determining the relativedimensions of the wave form under investigation. This curved face plateand its external graticule result in a distortion of the wave form imageand in parallax of the graticule scale image, as viewed by a camera ordirectly by a human observer.

In addition, conventional cathode ray tubes are provided with aresistance coating of aquadag or other low oxidation temperature carbonmaterial on the interior surface of the body portion of the envelope,which in some instances is connected to function merely as an extensionof the second anode in the electron gun and 3,207,936 Patented Sept. 21,1965 in other cases as a post acceleration anode to increase thevelocity of the electron beam after deflection of such beam by theelectrical signal under examination. Heretofore, the post accelerationanode has been provided in the form of either a plurality of spaced,insulated, uniform thickness coating portions with each of such coatingportions at difierent potentials, or a single uniform thickness coatingin the shape of a helix, to produce an electrical potential gradient ofincreasing magnitude from the electron gun to the fluorescent screen ofthe cathode ray tube. However, these conventional multi-portion andhelical resistance coatings do not allow uniform acceleration of theelectron beam and do not provide a uniform electric field within a givencross-section of the tube, respectively. Also, the carbon material ofsuch coatings oxidizes if high temperature is used during the bake outevacuation process, as is necessary for eflicient out-gassing to removeabsorbed gases in the cathode ray tube.

The above discussed disadvantages of conventional cathode ray tubes areovercome by the envelope structure of the present invention. Thus, theuse of an envelope with a ceramic body portion provides the envelopewith suflicient strength so that it may be made of a thin, substantiallyuniform, wall thickness with one end having a hollow cross-section inthe shape of a rectangle which may be sealed to a transparent glass faceplate in the form of a flat plate of the same configuration as such bodycross-section by means of a glass frit seal having a thermal coefficientof expansion substantially the same as, and a softening temperaturesubstantially below, that of such ceramic and transparent glass in orderto eliminate the wasted space of conventional glass tubes. The graticulescale may be provided directly on the interior surface of the fla-t faceplate which can be edge-lighted, to eliminate the graticule imageparallax and wave shape image distortion of conventional tubes. Also,the post acceleration anode coating may be made of non-carbon refractorymaterial so that high temperature evacuation is possible, and suchcoating may be formed with a variable thickness which decreases in valuefrom the end of the coating farthest from the face plate toward the endnearest the face plate so that the resistance per square of such coatingincreases in the same direction. This graduated resistance coating maycompletely cover the interior surface of the ceramic body portion fromone end of such coating to the other end thereof and thereby provides amore uniform electric field within a given cross-section and allows moreuniform acceleration of the electron beam.

Therefore, one object of the present invention is to provide an improvedelectron beam display device employing an envelope portion made ofceramic material.

Another object of the present invention is to provide an improvedelectron beam display device having an envelope including a body portionof ceramic material with one end having a hollow cross-section in theshape of a right-angle parallelogram, a face plate portion oftransparent glass material in the form of a fiat plate having the shapeof a right-angle parallelogram corresponding to that of such body endcross-section, and a seal portion of a material having a thermalcoefiicient of expansion similar to, and a softening temperaturesubstantially below, that of such ceramic and such transparent glassattaching such face plate portion to such body portion.

A further object of the invention is to provide an improved cathode raytube having a graticule scale formed on the inner surface of asubstantially flat, transparent glass face plate portion of the envelopeof such cathode ray tube upon which the fluorescent screen thereof issupported over such graticule scale, such face plate being adapted totransmit light through the edge surrounding the periphery thereof intosuch face plate in order to illuminate such graticule.

Another object of the invention is to provide an improved cathode raytube having an anode coating of electrical resistance material,containing Cr O Fe O TiO and ceramic material, upon the internal surfaceof a portion of the envelope of such tube.

Still another object of the present invention is to provide an improvedcathode ray tube having an envelope with an electrical resistancecoating of non-carbon refractory material upon the interior surface ofthe funnelshaped body portion of such envelope so that the thickness ofsuch coating varies with distance from the face plateportion of suchenvelope by increasing in magnitude from an end nearest to such faceplate toward an end farthest from such face plate so that the resistanceper square of such coating decreases in the same direction away fromsuch face plate, and such coating is connected to provide an electricalpotential gradient so that such coating functions as a post deflectionacceleration anode to accelerate the electron beam in such cathode raytube toward such face plate.

A still further object of the invention is to provide an improvedenvelope for use in a cathode ray tube including a glass neck portion inthe shape of ahollow circular cylinder, a ceramic body portion havingone end of a hollow circular cross-section sealed to such stem portionby a glass frit material with a thermal coefiicient of expansionsubstantially the same as, and a softening temperature substantiallybelow, that of such ceramic body and such glass stem and having a secondend with a hollow cross-section in the shape of a rectangle, and a faceplate portion of transparent glass in the form of a fiat plateconforming to the shape of such second end of such body portion andsealed to such second end by a glass frit material having a thermalcoeflicient of expansion similar to, and a softening temperaturesubstantially below, that of such ceramic body and such glass faceplate.

Additional objects and advantages of the present invention Will becomeapparent after referring to the following detailed description ofcertain preferred embodiments thereof and to the attached drawings ofwhich:

FIG. 1 is a side view of one embodiment of a cathode ray tube made inaccordance with the present invention;

FIG. 2 is a partial top view of the cathode ray tube of FIG. 1 with aportion of the envelope broken away;

FIG. 3 is a front view taken along the line 33 of FIG. 1;

FIG. 4 is a sectional view taken along the line 4-4 of FIG. 3;

FIG. 5 is a sectional view of part of a glass-to-ceramic seal in thecathode ray tube envelope of FIG. 2;

FIG. 6 is a partial sectional view taken along the line 66 of FIG. 3showing one embodiment of the graticule;

FIG. 7 is a partial view of FIG. 6 showing another embodiment of thegraticule;

FIG. 8 is a partial side view of another embodiment of a cathode raytube made in accordance with the present invention;

FIG. 9 is a top view of the cathode ray tube of FIG. 8 with portions ofthe envelope broken away;

FIG. 10 is a front view of the cathode ray tube of FIG. 8 taken alongthe line 1010;

FIG. 11 is a partial sectional view taken along the line 1111 of FIG. 8;and

FIG. 12 is a graph showing the resistance characteristic of thegraduated resistance coating used in the cathode ray tube of FIGS. 8 to11.

' One embodiment of the envelope structure of the present invention isshown in FIGS. 1 to 6 which disclose a cathode ray tube having a hollow,evacuated envelope 10 of electrical insulating material including afunnel-shaped body portion 12, a flat face plate portion 14 and acylindrical stem portion 16. The envelope 10 contains a conventionalelectron gun and conventional electrostatic de fiection plates (notshown) inside the stem portion 16 with electrical leads 18 connected tothe horizontal and vertical deflection plates extending through aconventional flame seal 20 joining two cylindrical members which formsuch stem portion. Other electrical leads 22 connected to the electrongun electrodes extend through the end of stem portion 16 remote frombody portion 12 so that they are supported in a socket 24 of insulatingmaterial mounted on the rear end of envelope 10. The envelope bodyportion 12 is made of ceramic insulating material in the shape of atapered funnel formed of a cone frustrum joined to a rectangularcylinder, and has a smaller end with a hollow circular cross-sectionattached to the stem portion 16 and a larger end with a hollowrectangular cross-section attached to the face plate 14 supportingfluorescent screen 25 of the cathode ray tube.

A resistance coating 26 of substantially uniform thickness may beprovided on the internal surface of envelope body portion 12, as shownin FIG. 2, which is electrically connected to the second anode in theelectron gun to serve as an extension of such anode and provides asubstantially uniform electrical field within such body portion 12 forthe electron beam of the mono-acceleration type cathode ray tube. A pairof thin layers 28 and 30 of silver, or similar conducting material, maybe coated over each end of resistance coating 26 for a short distance todefine with regularity the outline of the effective anode formed therebyand to provide a good electrical connectio thereto from the second anodethrough a spring support member 31 as shown in FIG. 5. This uniformresistance coating 26 may be made of conventional low temperaturematerial, such as aquadag or other carbon material, or it may becomposed of the non-carbon, refractory material hereafter described withreference to FIGS. 8 to 11.

The face plate 14 may be made of a clear transparent glass material inthe form of a substantially flat rectangular plate having a shape, asshown in FIGS. 3 and 4, conforming to that of the larger end of ceramicbody portion 12 to which it is attached. A graticule scale 32 may beprovided on the inner surface of the face plate 14 by printing lines ofglass frit thereon and fusing such frit lines onto the face plate beforethe layer of phosphor material forming fluorescent screen 25 is appliedto such surface over such graticule scale, as shown in FIG. 6.Alternatively, the graticule lines may be chemically etched ormechanically scribed as notches 33 in the surface of the face plate, asshown in FIG. 7, or they may be applied as a paint of light reflectingmaterial. This use of a separate flat face plate 14 enables the phosphorlayer 25 and the graticule scale 32 to be applied to such face platebefore it is sealed to the envelope body portion 12 so that it can bemore easily processed than when a conventional all glass tube is used.

The graticule scale 32 may be edge-lighted with a light sourcepositioned adjacent a portion of the edge surrounding the periphery ofthe face plate 14 so that sulficient light is transmitted through suchedge portion into such face plate to illuminate the graticule lines. Asshown in FIG. 3, if the light source is located at a position remotefrom the edge of the face plate 14, a flange member 34 of cleartransparent plastic or similar material in the form of a flat, squareplate, may be attached to such face plate edge by a transparent epoxyresin glue or the like so that such flange member functions as a lightguide to efliciently transmit light from the light source into the edgeof the face plate. This flange member 34 may be provided with twoU-shaped notches 36 and 38 in the upper external edge portion thereof toaccommodate two light bulbs, and with a conventional coating of lightreflecting material (not shown), such as aluminum, silver or whiteenamel, on the remainder of the external edge of such flange memberexclusive of such notches. Also, it may be desirable to provide such alight reflecting coating on the edge of the face plate 14 when flangemember 36 is not used.

The flat glass face plate 14 may be attached to the rectangular end ofceramic body portion 12 by means of a vacuum tight seal 40 surroundingfluorescent screen 25 to form the butt joint shown in FIG. 6. This seal40 may be made of a glass frit having a thermal coeflicient of expansionapproximately the same as that of the ceramic in body portion 12 and theglass in face plate 14 and a softening or sealing temperaturesubstantially below that of such ceramic and such glass. Another glassfrit seal 42, similar to seal 40, may be provided to form the butt jointbetween the circular end of ceramic body portion 12 and glass stemportion 16 of the envelope, as shown in FIG. 5, since the glass materialof such stem portion may be the same as that of the face plate 14. Anysuitable glass and ceramic system may be used having the above discussedcharacteristics. For example, the body portion 12 may be made offorsterite ceramic having a composition by weight of approximately:

Percent MgO 28 Talc 60 Kaolin 12 The face plate portion 14 and the stemportion 16 may be made of soda lime glass or common lead glasscommercially available from Corning Glass Works as Corning No. 0080 andNo. 0120, respectively. This soda lime glass has a composition by weightof approximately:

Percent SiO 73.6 Na O 16.0 K .6 CaO 5.2 MgO 3.6 A1 0 1.0

The glass frit of seals 40 and 42 may be made of a devitrifiable glass,such as the lead-zinc-borate type glass disclosed in US. Patent No.2,889,952, issued to S. A. Claypoole on June 9, 1959, having a thermalcoeflicient of expansion similar to that of the forsterite ceramic ofapproximately 93 10-' per C. within the temperature range of 25 to 450C. and a low softening temperature on the order of 420 to 450 C. Onesuch devitrifiable glass is commercially available from Corning GlassWorks as Pyroceram Cement No. 7572 and may be applied as seals 40 and 42in the manner disclosed in the above patent.

It should be noted that this devitrified glass is often referred to as aglass-ceramic because it possesses similar characteristics to both ofthese classes of materials. However, the term glass frit is definedherein as including such a devitrified glass throughout the presentapplication. Also, the term ceramic material is hereby define-d asdistinguishing from glass in that the former is a crystalline materialwhile the latter is a supercooled liquid, noncrystalline material.

Another embodiment of a cathode ray tube made in accordance with thepresent invention is shown in FIGS. 8 to 11. This post acceleration typeof cathode ray tube is similar to that shown in FIGS. 1 to 6 except theuniform resistance coating 26 is replaced by a graduated resistancecoating 44 of varying thickness on the inner surface of a funnel-shapedenvelope body portions 46 having a different configuration than bodyportion 12, including parabolic curved side walls. Also, a differentshaped face plate 48 without the flange member light guide 34, isprovided of rectangular configuration but with a smaller heightdimension so that the graticule scale 32 is 6 cm. by 10 cm., rather than8 cm. by 10 cm. as shown in FIG. 3.

The graduated resistance coating 44 varies in thickness by decreasing inmagnitude from a maximum at the end thereof adjacent the stem portion 16to a minimum at the end adjacent the face plate 48 which results in theresistance per square of such coating increasing in the same directionfrom a minimum near stem portion 16 to a maximum near face plate 48. Theend of this graduated resistance coating 44 adjacent stem portion 16 ofthe envelope, is connected to the second anode of the electron gun inthe same manner as uniform resistance coating 26 by means of the springmember 31 and conductive coating 28 shown in FIG. 5, While the other endof such graduated resistance coating adjacent face plate 48 is connectedto a source of greater positive DC. voltage than such second anode bymeans of an electrical connector 50 extending through a hole in envelopebody portion 46. Therefore, an electrical potential gradient isestablished along the surface of graduated resistance coating 44 so thatsuch resistance coating functions as a post deflection accelerationanode which increases the velocity of the electron beam after itsdeflection by the electrical signals applied to the electrostaticdeflection plates, so that such electron beam increases in velocityafter deflection as it travels along such resistance coating toward faceplate 48 and produces a higher intensity light image on fluorescentscreen without decreasing the deflection sensitivity of the tube.

As shown in FIG. 11, the electrical connector 50 may be in the form of asolid plug 52 made of ceramic material similar to that of envelopeportion 46 and having a coating 54 of electrically conducting material,such as silver, on the external surface thereof. This coated plug may beinserted into a hole made in envelope portion 46 adjacent conductivecoating and secured to such body portion by a vacuum tight seal 56 inthe form of a glass frit, which may have a composition similar to thatof the material used in seals and 42 of this post acceleration cathoderay tube, or it may be made of a different material suitable for themetal to ceramic seal. An additional silver coating 58 may be appliedover the end of plug 52 after it is attached to the envelope portion 46making contact between conductive coating 54 and conductive coating 30to prevent the glass frit 56 from insulating coating 54 from coating 30.

A different ceramic and glass system may be used to make the postacceleration cathode ray tube of FIGS. 8 to 11. For example, the bodyportion 46 of the envelope may be made of an alumina ceramic having acomposition by weight of approximately:

Percent A1 0 Talc 4 Ball clay 7 Nepheline syenite 4 The stem portion 16and the face plate portion 48 of the envelope may be formed of azirconium silicate glass such as that commercially available fromCorning Glass Works under Corning No. 7280 having a composition byweight of approximately:

Percent SiO 70 ZrO l7 N320, K20 13 7 No. 7541. However, another glassfrit has been discovered which has been found to be suitable and isbelieved to be heretofore unknown, having a composition by weight ofapproximately:

This new undevitrifiable glass has a sealing temperature on the order of760 to 788 C. and a thermal coefficient of expansion of approximately 65l0-' cm./cm. per C. at 25 to 450 C. temperature.

For proper operation as a post acceleration anode the graduatedresistance coating 44 should have a resistance characteristic similar tothat of the theoretical ideal curve 60 in FIG. 12. This curve is a plotof percent of the total resistance of coating 44 verses the distance ininches from its face plate end measured from coating 30. Note that inthe region of to 1 inch there is a resistance change of about 17% whilein the region of 7 to 8 inches there is a resistance change of onlyabout 7%. Therefore, the theoretical ideal resistance per square ofcoating 44 decreases from a maximum value near face plate 48 to aminimum value near stem portion 16. Since thickness varies inverselywith resistance, the theoretical ideal thickness of coating 44 increasesfrom a minimum value near face plate 48 to a maximum value near stemportion 16. It should be noted that curve 60 merely represents thetheoretical ideal characteristic of graduated resistance coating 44 andthat operable coatings may have actual characteristic curves whichdeviate by several percent above or below such ideal curve. Also, thetotal resistance of resistance coating 44 may be anywhere between 100and 2000 megohms for operable tubes and this total resistance isrepresented on the graph by the 100% resistance point.

This graduated resistance coating 44 may be formed of conventionalmaterials, such as aquadag or other carbon materials. However, it hasbeen found that such carbon coatings are damaged by the high temperatureused in the out-gassing process so that they are unsuitable whenextremely high temperatures are used, as is necessary for efiicientremoval of the absorbed gases.

Therefore, the material of graduated resistance coating r 44 or uniformresistance coating 26, should be a noncarbon, refractory material whichdoes not oxidize or melt at extremely high temperatures. Such a materialbelieved to be heretofore unknown has been discovered. This newresistance material has composition by weight of approximately:

Percent CIZO3 2.6 Fg03 Ti0 2.4 Feldspar 17.3 Ball clay 13.2 Flint 14.3Whiting (prepared CaCo 15.2

It should be noted that this new resistance coating may be consideredbasically a mixture of two different materials which are (1) aconducting material formed by the first three compounds listed-totalling40% and (2) a ceramic material consisting of the last four compoundslistedtotalling 60%. This resistance film may be applied by anyconventional spraying method and then heated to fuse it to the envelopewall.

Various details of the above described preferred embodiments of thepresent invention may be varied without departing from the spirit of theinvention. Thus, the stem portion 16 may be formed integrally with thebody portions 12 and 46 so that it too can be made of ceramic material.The face plate end of such envelope body portion may be made of anydesirable configuration to provide a hollow cross-section of anyconvenient shape including a right-angle parallelogram in the form of asquare or rectangle, and the face plates attached thereto may likewisebe formed of any convenient shape. The light guide flange 34 may beformed integrally with the face plate so that it too is made of glass,or it can be eliminated entirely. The butt joints formed by seals 40 and42 may be of a different type, for example, seal 42 may be in the formof a slip joint. Therefore, the scope of the present invention should bedetermined only by the following claims.

We claim:

1. An electron beam display device, comprising:

an envelope having a hollow body portion made of ceramic material, aface plate portion made of transparent glass in the form of asubstantially flat plate shaped to conform to one end of said bodyportion,

and a seal portion attaching said face plate portion to said one end ofsaid body portion with said seal portion being made of fused glassmaterial different from said transparent glass but having a thermalcoefficient of expansion similar to that of said ceramic and saidtransparent glass;

a fluorescent screen including a layer of phosphor material supported onthe flat inner surface of said glass face plate portion inside saidenvelope;

at source of electrons positioned within said envelope at one endthereof remote from said face plate;

means to accelerate said electrons and to focus said electrons into anelectron beam; and

means to deflect said electron beam in response to an electrical signalbefore said beam strikes said fluorescent screen on said face plate.

2. An electron beam display device, comprising:

an envelope having a body portion made of ceramic material in the shapeof a hollow funnel with the larger end of said body portion being of asubstantially right-angle parallelogram configuration, a face plateportion made of transparent glass in the form of a substantially fiatplate shaped to conform to said larger end of said body portion, and aseal portion attaching said face plate portion to said larger end ofsaid body portion with said seal portion being made of a fused glassfrit material different from that of said transparent glass but having athermal coefficient of expansion similar to that of said ceramic andsaid transparent glass;

a fluorescent screen including a layer of phosphor material supported onthe flat inner surface of said glass face plate portion inside saidenvelope;

a source of electrons supported within said envelope at the end thereofremote from said face plate;

means to accelerate said electrons and to focus said electrons into anelectron beam; and

means to deflect said electron beam in response to an electrical signalbefore said beam strikes said fluorescent screen.

3. An electronbearn display device, comprising:

an envelope having a body portion made of ceramic material with one endof said body portion being of a substantially rectangular hollowcross-section, and a face plate portion made of transparent glass in theform of a fiat plate of a shape substantially conforming to that of saidcross-section and attached to said one end of said body portion by aseal portion made of a fused glass frit material having thermalcoefficient of expansion similar to, and a softening temperature below,that of said ceramic and said transparent glass;

a fluorescent screen including a layer of phosphor material on the flatinner surface of said glass face plate portion inside said envelope;

a coating of electrical resistance material on the inner surface of saidceramic body portion of said envelope, having a variable thickness whichincreases in value from the end nearest to said face plate toward theend farthest from said face plate so that the resistance per square ofsaid coating decreases in the same direction, and connected to functionas a post deflection acceleration anode by providing an electricalpotential gradient of increasing magnitude for the electron beam in saiddisplay device as it approaches said face plate;

a source of electrons supported within said envelope at the end thereofremote from said face plate;

means to accelerate said electrons and to focus said electrons into anelectron beam; and

means to deflect said electron beam in response to an electrical signalbefore said beam passes through said post acceleration anode and strikessaid fluorescent screen.

4. An electron beam display device, comprising:

an envelope having a body portion made of ceramic material with one endof said body portion being of a substantially rectangular configuration,and a face plate portion made of transparent glass in the shape of asubstantially flat rectangular plate attached to said rectangular end ofsaid body portion by a seal portion made of a fused glass frit materialhaving a thermal coefficient of expansion similar to, and a softeningtemperature below, that of said ceramic and said transparent glass;

a graticule scale formed by a plurality of straight lines intersectingat right angles on the inner surface of said face plate portion insidesaid envelope;

a fluorescent screen including a layer of phosphor material on the innersurface of said face plate over said graticule scale;

means for projecting light into said face plate portion through the edgesurrounding the periphery thereof in order to illuminate said graticulescale, including a plastic flange member attached at its inner edge tosaid edge of said face plate so that said flange member may function asa light guide to transmit light from an external source into said faceplate;

a source of electrons supported within said envelope at the end thereofremote from said face plate;

means to accelerate said electrons and to focus said electrons into anelectron beam; and

means to deflect said electron beam in response to an electrical signalbefore said beam strikes said fluorescent screen.

5. An electron beam display device, comprising:

an envelope having a hollow body portion made of ceramic material withone end formed as a rectangular cylinder joined to the other end of saidbody portion formed in the shape of the frustrum of a cone, a tubularstern portion made of glass in the shape of a circular cylinder attachedto said other end of said body portion by a first seal of fused glassmaterial different from the stem glass but having a thermal coeflicientof expansion similar to that of said ceramic and said stern glass, and aface plate portion made of transparent glass in the form of asubstantially flat plate shaped to conform to said one end of said bodyportion and attached to said one end of said body portion by a secondseal made of fused glass material different from the face plate buthaving a thermal coefficient of expansion similar to that of saidceramic and said face plate glass;

a fluorescent screen including a layer of phosphor material supported onthe flat inner surface of said glass face plate portion inside saidenvelope;

a source of electrons positioned Within said envelope 10 at one endthereof remote from said face plate; means to accelerate said electronsand to focus said electrons into an electron beam; and

means to deflect said electron beam in response to an electrical signalbefore said beam strikes said fluorescent screen on said face plate.

6. An electron beam display device, comprising:

an envelope having a body portion made of ceramic material with one endof said body portion being of a substantially rectangular hollowcross-section, and a face plate portion made of transparent glass in theform of a flat plate of a shape substantially conforming to that of saidcross-section and attached to said one end of said body portion by aseal portion made of a fused glass frit material having thermalcoeflicient of expansion similar to, and a softening temperature below,that of said ceramic and said transparent glass;

a fluorescent screen including a layer of phosphor material on the flatinner surface of said glass face plate portion inside said envelope;

a coating of electrical resistance material on the inner surface of saidceramic body portion of said envelope, having a variable thickness whichincreases in value from the end nearest to said face plate toward theend farthest from said face plate so that the resistance per square ofsaid coating decreases in the same direction, and connected to functionas a post deflection acceleration anode by providing an electricalpotential gradient of increasing magnitude for the electron beam in saiddisplay device as it approaches said face plate;

means to connect said resistance coating as a post acceleration anode toa source of electrical potential, including a conducting layer ofelectrically conducting material of uniform thickness on said envelopebody portion over said end of said resistance coating nearest said faceplate, and a plug of ceramic material provided with a coating ofconducting material, sealed in a hole through said envelope body portionat a position adjacent said conducting layer so that the conductingcoating on said plug makes electrical contact with said conductinglayer;

a source of electrons supported within said envelope at the end thereofremote from said face plate;

means to accelerate said electrons and to focus said electrons into anelectron beam; and

means to deflect said electron beam in response to an electrical signalbefore said beam passes through said post acceleration anode and strikessaid fluorescent screen.

7. An electron beam display device, comprising:

an envelope having a body portion made of ceramic material with one endof said body portion being of a substantially rectangular hollowcross-section, and a face plate portion made of transparent glass in theform of a flat plate of a shape substantially conforming to that of saidcross-section and attached to said one end of said body portion by aseal portion made of a fused glass frit material having thermalcoefficient of expansion similar to, and a softening temperature below,that of said ceramic and said transparent glass;

a fluorescent screen including a layer of phosphor material on the flatinner surface of said glass face plate portion inside said envelope;

a coating of electrical resistance material containing Fe O TiO Cr O anda ceramic material, on the inner surface of said ceramic body portion ofsaid envelope, having a variable thickness which increases in value fromthe end nearest to said face plate toward the end farthest from saidface plate so that the resistance per square of said coating decreasesin the same direction, and connected to function as a post deflectionacceleration anode by providing an electrical potential gradient ofincreasing magnitude for the electron beam in said display device as itapproaches said face plate;

a source of electrons supported within said envelope at the end thereofremote from said face plate;

means to accelerate said electrons and to focus said electrons into anelectron beam; and

means to deflect said electron beam in response to an electrical signalbefore said beam passes through said post acceleration anode and strikessaid fluorescent screen. 8. An envelope for use in an electron beamdisplay device, comprising:

a body portion made of ceramic material and having one end of a hollowcross-section substantially in the shape of a right-angle parallelogram;

a face plate portion made of transparent glass material in the form of athin, flat plate having sides substantially corresponding in shape tosaid one end of said body portion with a graticule formed on the surfaceof one of said sides; and

a seal portion made of a fused glass material different from saidtransparent glass but having a thermal coefiicient of expansion similarto that of said transparent glass and said ceramic, attaching said faceplate portion to said body portion so that said graticule is positionedon the interior surface of said envelope.

9. An envelope for use in a cathode ray tube, comprising:

a body portion made of ceramic material in the shape of a funnel andhaving its larger end of a substantially rectangular cross-section;

a face plate portion made of transparent glass material in the shape ofa substantially flat rectangular plate with a graticule formed on thesurface of one side thereof;

a seal portion of fused glass frit material different from saidtransparent glass but having a thermal coefficient of expansion similarto that of said ceramic and said transparent glass, said seal portionattaching said face plate portion to said larger end of said bodyportion so that said graticule is positioned on the interior surface ofsaid envelope; and

means for projecting light into said face plate portion through the edgesurrounding the periphery thereof in order to illuminate said graticule.

10. An envelope for use in a cathode ray tube, comprising:

a body portion made of ceramic material and having one end of asubstantially rectangular hollow crosssection;

a face plate portion made of transparent glass material in the shape ofa substantially flat rectangular plate with a graticule formed by fusedglass lines coated on the surface of one side thereof;

a seal portion made of a fused glass frit material having a thermalcoefficient of expansion similar to, and a softening temperature below,that of said transparent glass and said ceramic, said seal portionattaching said face plate portion to said one end of said body portionso that said graticule is positioned on the interior surface of saidenvelope; and

means for projecting light into said face plate portion through the edgesurrounding the periphery thereof in order to illuminate said graticule.

11. An envelope for use in a cathode ray tube, comprising:

a body portion made of ceramic material and having one end of asubstantially rectangular hollow crosssection;

a face plate portion made of transparent glass material in the shape ofa substantially fiat rectangular plate 12 with a graticule formed bynotches in the surface of one side thereof;

a seal portion formed by a fused glass frit material different from saidtransparent glass, attaching said face plate portion to said bodyportion so that said graticule is positioned on the interior surface ofsaid envelope; and

means for projecting light into said face plate portion through the edgesurrounding the periphery thereof in order to illuminate said graticule.

An envelope for use in a cathode ray tube, comprising:

a body portion made of ceramic material in the shape of a funnel andhaving its larger end of a substantially rectangular cross-section;

a face plate portion made of transparent glass material in the shape ofa substantially flat rectangular plate with a graticule formed on thesurface of one side thereof;

a seal portion of fused glass frit material having a thermal coefiicientof expansion similar to, and a sealing temperature substantially below,that of said ceramic and said transparent glass, attaching said faceplate portion to said larger end of said body portion so that saidgraticule is positioned on the interior surface of said envelope; and

means for projecting light into said face plate portion through the edgesurrounding the periphery thereof in order to illuminate said graticuleincluding a transparent plastic flange member attached at its inner edgeto said edge of said face plate so that said flange member may functionas a light guide to transmit light from a remote external light sourceinto said face plate.

13. An envelope for use in an electron beam display device, comprising:

a body portion made of ceramic material and having one end of a hollowcross-section substantially in the shape of a right-angle parallelogram;

a face plate portion made of transparent glass material in the form of athin, flat plate having sides substantially corresponding in shape tosaid one end of said body portion with a graticule formed on the surfaceof one of said sides; and

a seal portion made of a fused glass material containing PbO, A1 0 SiO B0 and ZnO, having a termal coeflicient of expansion similar to, and asealing tem perature substantially below, that of said transparent glassand said ceramic, attaching said face plate portion to said body portionso that said graticule is positioned on the interior surface of saidenvelope.

14. An envelope for use in an electron beam display device, comprising:

a body portion made of ceramic material and having one end of a hollowcross-section substantially in the shape of a right-angle parallelogram;

a face plate portion made of transparent glass material in the form of athin, flat plate having sides substantially corresponding in shape tosaid one end of said body portion;

a first seal portion made of a fused glass frit different from saidtransparent glass but having a termal coeflicient of expansion similarto that of said transparent glass and said ceramic, said first sealportion attaching said face plate portion to said body portion so thatsaid graticule is positioned on the interior surface of said envelope;

a tubular stem portion of glass; and

a second seal portion similar to said first seal portion attaching saidstem portion to the other end of said body portion.

15. An anode for uniformerly accelerating electrons as they travel alongthe surface of said anode spaced therefrom, comprising:

a support member of electrical insulating material; and

13 14 a graduated resistance coating of electrical conducting ReferencesCited by the Examiner material on said support member With the thicknessUNITED STATES PATENTS of said coating varying from a maximum at one endthereof to a minimum at the other end thereof so that g gsii et "Ti; theelectrical resistance per square of said coating 5 2207841 7 M0 Xincreases from a minimum value at said one end to a 2:210:131 8/40scharfnagel maximum Value at Said other 2,251,984 8/41 Cleaver et al 17s7.s4 16. An anode for uniformrly accelerating electrons as 2330604 3Messner 17 7 4 hey travel along the surface of said anode space there- 12 434 19 1 43 c i 31 5-44 from, comprising: 0 2,629,066 2/53 Eitel et.al. 220-2.1 X a support member of electrical insulating material; and2,695,241 11/54 Calis 106-53 a graduated resistance coating ofelectrical conducting 2,812,466 11/57 Murdock 3133 17 materialcontaining a mixture of Fe O Cr O TiO 2,878,408 3/59 Ri-shell 313217 andceramic material on said support member with 2,889,95 CI YPOOI thethickness of said coating varying from a maxi- 15 r g mum at one endthereof to a minimum at the other 2,962,452 11/60 Counts end thereof sothat the electrical resistance per square of said coating increases froma minimum value at DAVID GALVIN Prlmary Examinersaid one end to amaximum value at said other end. ARTHUR GAUSS, GEORGE N. WESTBY,Examiners.

1. AN ELECTRON BEAM DISPLAY DEVICE, COMPRISING: AN ENVELOPE HAVING AHOLLOW BODY PORTION MADE OF CERMERIC MATERIAL, A FACE PLATE PORTION MADEOF TRANSPARENT GLASS IN THE FORM OF A SUBSTANTIALLY FLAT PLATE SHAPED TOCONFORM TO ONE END OF SAID BODY PORTION, AND A SEAL PORTIN ATTACHINGSAID FACE PLATE PORTION TO SAID ONE END OF SAID BODY PORTION WITH SAIDSEAL PORTION BEING MADE OF FUSED GLASS MATERIAL DIFFERENT FROM SAIDTRANSPARENT GLASS BUT HAVING A THERMAL COEFFICIENT OF EXPANSION SIMILARTO THAT OF SAID CERAMIC AND SAID TRANSPARENT GLASS; A FLUORESCENT SCREENINCLUDING A LAYER OF PHOSPHOR MATERIAL SUPPORTED ON THE FLAT INNERSURFACE OF SAID GLASS FACE PLATE PORTION INSIDE SAID ENVELOPE; A SOURCEOF ELECTRONS POSITIONED WITHIN SAID ENVELOPE AT ONE END THEREOF REMOTEFROM SAID FACE PLATE; MEANS TO ACCELERATE SAID ELECTRONS AND TO FOCUSSAID ELECTRONS INTO AN ELECTRON BEAM; AND MEANS TO DEFLECT SAID ELECTRONBEAM IN RESPONSE TO AN ELECTRICAL SIGNAL BEFORE SAID BEAM STRIKES SAIDFLUORESCENT SCREEN ON SAID FACE PLATE.